Maj. Gen. Harold J. Greene. A U.S. official has identified the senior officer killed in Afghanistan on Aug. 5, as Greene, the highest-ranking American officer killed in combat since 1970. Greene was the deputy commanding general, Combined Security Transition Command-Afghanistan. An engineer by training, Greene was involved in preparing Afghan forces for the time when U.S.-coalition troops leave at the end of this year. U.S. Army via AP file

The U.S. Army general gunned down in Afghanistan on Tuesday was identified as Maj. Gen. Harold Greene, sources told NBC News. Greene, a two-star general from Falls Church, Virginia, was the deputy commanding general for the Combined Security Transition Command in Afghanistan, which is in charge of the training and development of the Afghan National Security Forces.

Greene, 55, is the highest-ranking Army general killed in an overseas combat zone since the Vietnam War. He was a native of upstate New York and graduated from Rensselaer Polytechnic Institute in Troy, New York, in 1980 and earned a doctorate from the University of Southern California in materials science, according to his military biography.

A lone gunman in Afghan military clothing is accused of ambushing more than a dozen Western soldiers at the Afghanistan National Military Academy in Kabul. About half of those wounded were Americans. Germany's military said in a statement that 15 troops had been wounded in the attack, including a German brigadier general, according to The Associated Press.

The husband and father was remembered as a family man who loved serving his country. “He was a good guy,” Ret. Army Col. Duane Myers told Stars and Stripes. “Harry was loved.”

"The family wants us to know they believe America has lost a true hero today," said Lt. Col. Juanita Chang of Army Public Affairs. "He believed in what he was doing over there".

The Pentagon did not immediately confirm the identity of the deceased general, although Army Chief of Staff Gen. Ray Odierno released a statement giving his condolences to the Greene family and the other injured soldiers.

“These soldiers were professionals, committed to the mission. It is their service and sacrifice that define us as an Army,” Odierno said. “We remain committed to our mission in Afghanistan and will continue to work with our Afghan partners to ensure the safety and security of all coalition soldiers and civilians,” he added.